The present invention relates to a method for the production of wood studs or the like generally oblong pieces comprising a central web and opposite flanges attached thereto as disclosed in the preamble to appended claim 1. The invention further relates to a system comprising such studs as well as to further methods for attaching, between upper and lower surfaces, vertical studs of the kind as disclosed above.
In building industry wood is traditionally used for structures of many kinds, but the use of wood, e.g., for posts and cross-bars has in course of time declined in favor of metal studs. The reason for this has been mainly economical, since metal studs nowadays can be manufactured to a more favorable price than wooden studs having the same properties. Moreover, metal studs have the advantage that they are lighter than usual wooden studs and the do not, for example, twist. To this is normally added a certain possibility to pile the studs. Again, a clear disadvantage for metal studs, on the other hand, is that any shaping of the material requires special tools and arrangements, and the result of such a shaping usually will be uneven and jagged. Further, an attachment of, e.g., wallboards to the studs requires special arrangements. Thus, there would exist a market for wooden studs, provided that the costs could be kept low and the studs structurally would be more shape permanent than is the case with known studs and posts.
In mechanical wood processing like sawing the primary raw material always will be round timber, wherefrom one or several wood blocks are taken out in the form of parallelepipeds having, respectively, two opposite parallel planar surfaces. Later on this planar wood can be processed and thus different kinds of more finished products can be obtained, but the out-side boards, i.e. wood pieces normally comprising only one planar side true to gauge while the opposite side at most comprises a planar surface of reduced dimensions and usually only more or less semi-round portions, can normally not be effectively used. To some extent such defective sawn goods has been used as basic material for small dimension laths and the like, but often the useful use is restricted to a function as fire wood or, in a restricted scale, as raw material for the cellulose industry. A common way to further refine this waste wood material is to cut it to chips, in which case all inherent structure will be lost.
Besides the fact that this waste wood material normally comprises a round and a planar side a common problem is considered to reside therein that the dimension at the top end of the log is smaller than the dimension at the root end, for which reason one must take out log blocks having dimensions based on the top end in order to obtain full edge wood material. In this way further wood material is lost, for which a full price cannot be obtained. The price for the raw material discussed above mainly corresponds to the fire wood price, while the price for first class wood is much higher. Thus, this waste material would constitute a favorable raw material for, for example, studs and posts, provided that the manufacturing costs could be kept low and that a sufficient quality and shape permanence of the product could be maintained.
In the course of time one has tried to find different ways to utilize this waste wood material in a manner which makes use of the material""s strength properties. Thus, DE-Patent document No. 29 47 611 discloses a rather complicated arrangement for the manufacture of wooden slats or panels based on round timber by wetting the material, sawing it to boards having a conicity corresponding to that of the log, and by press gluing boards having an opposite conicity and arranged in a parallel manner to interconnect these boards to larger entities.
Again, SE-Patent application No. 9001337-6 discloses an arrangement where, in the same manner, it is suggested the use of opposite conicities in order to form, of four blocks, a hollow stud having a rectangular section, the inner of which being delimited by the outer surface and the conicity of the round timber. Finnish Patent No. 93567, again, discloses a way to form, by sawing round timber longitudinally into four sections, studs where one side comprises an inner V-shape.
The object of the present invention is to provide a method for producing studs and the like structures which can take up competition with corresponding metal studs and which effectively makes use of the waste material which is generated at mechanical wood processing and especially the material which is left over at round timber sawing when a wood block of a rectangular section is taken out.
According to the present invention the object is attained by the features indicated as characterizing ones in the appended claims. Thus, the inventive method is characterized in that the flanges are formed of essentially lath-like waste wood material generated at mechanical wood processing, wherein a contact surface is formed at the side of each respective opposite flange lath for co-operation with a surface shaped in a corresponding manner at a web also made of wood, suitably of waste wood material as discussed above, and that said contact surfaces are glued together, favorably under pressure, so that said web and said flanges connected thereto will constitute an essentially monolithic entity. The stud system according to the present invention is characterized in that said studs are formed in such a manner of pieces of essentially lath-like waste wood material which has been generated at mechanical wood processing that at least each respective flange comprises a longitudinal side portion which, in lateral section, is beveled, wherein a number of such flanges are glued to said web in order to form an essentially monolithic structure where said beveled side portions at opposite flanges are directed towards each other.
The methods for attaching the stud in accordance with the present invention is generally characterized in that one respective horizontal stud or crossbar manufactured by gluing together waste wood material to have an essentially U-shaped cross section is arranged at said upper and lower surfaces. That end of a vertical wooden stud or post which is directed towards said lower horizontal stud is shaped to essentially correspond to the inner section of said horizontal stud, so that the web of the vertical stud will extend between the flanges of the horizontal stud towards, favorably all the way to the web of said horizontal stud, in some case into openings between spaced web portions, while the ends of the flanges of the vertical post will lie close to the upper edge of said horizontal stud. The upper end of the vertical post, which post has been cut to a suitable length, is introduced into a locking device which co-operates with the horizontal stud arranged at the upper surface, said locking device comprising a resilient element, after which, if necessary, said vertical post is fixed in a manner known per se, e.g., by nailing, screwing, and/or gluing, to said horizontal studs. In most cases the post will, in practice, be slightly stressed or wedged in between the respective horizontal studs, so that any further attachment usually is quite unnecessary.
Alternatively, a U-shaped horizontal stud or crossbar manufactured by gluing together waste wood material is arranged only at one of said surfaces, while a thin-walled rail having an essentially U-shaped section and made of metal or the like is arranged at the opposite surface, said rail suitably having holes at least a the flanges. One end of the vertical post is shaped in accordance with the above while the other end is cut transversely to such a length that this end at the assembling will be located within the transverse U-shaped section of the metal stud approximately at its bottom or suitably at some distance therefrom, suitably up to 40 to 50 millimeters from said bottom for a flange width of 60 millimeters, in order to facilitate the introduction and attachment and in some cases also to allow a vertical motion for, e.g., an overlying structure and the horizontal stud attached thereto. The vertical post is introduced between said studs, after which, if necessary, said vertical post is fixed to said horizontal studs in a manner known per se.